The design of flexible and efficient mechanisms for proper placement and chaining of virtual network functions (VNFs) is key for the success of Network Function Virtualization (NFV). Most state-of-the-art solutions, however, consider fixed (and immutable) flow processing and bandwidth requirements when placing VNFs in the Network Points of Presence (N-PoPs). This limitation becomes critical in NFV-enabled networks having highly dynamic flow behavior, and in which flow processing requirements and available N-PoP resources change constantly. To bridge this gap, we present NFV-PEAR, a framework for adaptive VNF placement and chaining. In NFV-PEAR, network operators may periodically (re)arrange previously determined placement and chaining of VNFs, with the goal of maintaining acceptable end-to-end flow performance despite fluctuations of flow processing costs and requirements. In parallel, NFV-PEAR seeks to minimize network changes (e.g., reallocation of VNFs or network flows). The results obtained from an analytical and experimental evaluation provide evidence that NFV-PEAR has potential to deliver more stable operation of network services, while significantly reducing the number of network changes required to ensure end-to-end flow performance.

中文翻译：

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使用NFV-PEAR对虚拟网络功能进行自适应放置和链接

为虚拟网络功能（VNF）正确放置和链接而设计的灵活高效的机制是网络功能虚拟化（NFV）成功的关键。但是，在将VNF放置在网络存在点（N-PoP）中时，大多数最新解决方案都会考虑固定（且不可变）的流处理和带宽要求。对于具有高度动态流行为且启用了NFV的网络，并且其中流处理要求和可用N-PoP资源不断变化的情况，此限制变得至关重要。为了弥合这一差距，我们提出了NFV-PEAR，这是一种自适应VNF放置和链接的框架。在NFV-PEAR中，网络运营商可以定期（重新）安排先前确定的VNF放置和链接，目的是尽管流程处理成本和要求有所波动，但仍保持可接受的端到端流程性能。同时，NFV-PEAR试图使网络变化（例如，重新分配VNF或网络流量）最小化。通过分析和实验评估获得的结果提供了证据，表明NFV-PEAR有潜力提供更稳定的网络服务运行，同时显着减少了确保端到端流量性能所需的网络更改次数。